1. Field of the Invention
This invention relates to a terminal connection pin for solderless connections having a press-fit section which can be inserted into a contact through bore of a printed circuit board with a press-fit to provide a solderless electrical and mechanical connection between the terminal connection pin and the contact through bore of the printed circuit board, where the press-fit section is an extension of a connection pin having a generally square cross section with a groove parallel to its longitudinal axis and forms at least two axial contact paths opposite each other and having a limited flexibility.
2. Description of the Prior Art
To fasten solderless terminal connection pins in printed circuit boards without soldering and to connect them at the same time with the contact through bore, it is known in the art to shape a certain section of the shaft of such terminal connection pins, which usually have a square cross section, so that they are held in the contact through bore having a standardized diameter by press-fitting. Thus, the press-fit section of the terminal connection pin is obtained by indenting one or two notches facing each other so that they form contact paths reaching beyond the shaft which are pressed into the contact bore of the printed circuit board and held there similar to a grooved dowel pin.
In a known configuration, the press-fit section may have a cylindrical shape and the groove extends across the press-fit section parallel to its longitudinal axis. The depth and width of the groove is greater than half the diameter of the cylindrical outer surface of the press-fit section, as taught in German Patent DE-PS No. 29 37 883.
The disadvantage of this configuration is the fact that the pressure distribution along the circumference of the press-fit section cannot be controlled sufficiently after it has been inserted, even if the lateral areas of the press-fit section around the groove have a limited flexibility due to the groove. While this prevents tearing of the printed circuit board in the contact through bore area, as sometimes happens with rigid press-fit sections, it is done at the expense of an undefined contact formation between the press-fit section and the contact through bore of the printed circuit board. The areas of the press-fit section remaining around the groove are still so rigid in an axial direction that they cannot adapt to irregularities and tolerances of the contact through bore in this direction.
European Patent Publication EP-OS No. 105 044 teaches a configuration wherein the press-fit section is divided by a separation into three legs which are at such angles to each other that a triple axial contact path is formed. In addition, the contact paths may have a groove in order to obtain several individual contact points per contact path across the thickness of the printed circuit board.
This prior art terminal pin has the disadvantage that when the press-fit section is pressed into a contact through hole of the printed circuit board the separation slots become elongated and thus create different conditions in the press-fit section which result in different holding and contact forces. Defined holding and contact forces with tight tolerances cannot be implemented with this configuration.